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Routines |
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| 37613 | LD HL,64252 | Point HL at start of letter "A" graphic in character set | ||||||
| 37616 | EX DE,HL | Swap into DE | ||||||
| 37617 | LD B,26 | Load B with 26 | ||||||
| 37619 | PUSH BC | Store BC | ||||||
| 37620 | LD HL,(36488) | Load (video) memory location to start printing character into HL | ||||||
| 37623 | LD BC,2048 | Load B with 8 and C with zero | ||||||
| 37626 | LD A,(DE) | Read a byte of the character's graphic data... | ||||||
| 37627 | CP (HL) | ...compare to what is already displayed in display file at to-print location... | ||||||
| 37628 | JR Z,37631 | ...and if they're the same, jump to 37631 | ||||||
| 37630 | INC C | Else increase C | ||||||
| 37631 | INC H | Move down one pixel row (advance by 256 bytes) in display file | ||||||
| 37632 | INC DE | Advance to next pixel row of character of interest | ||||||
| 37633 | DJNZ 37626 | Loop back for next row | ||||||
| 37635 | LD A,C | Copy C into A... | ||||||
| 37636 | OR A | ...and if it is zero (i.e. current character in character set is same as character at to-print location in display file)... | ||||||
| 37637 | JR Z,37645 | ...jump ahead to 37645 | ||||||
| 37639 | POP BC | Restore BC | ||||||
| 37640 | DJNZ 37619 | Loop back for next character | ||||||
| 37642 | LD A,48 | Load A with 48 | ||||||
| 37644 | RET | Return | ||||||
| 37645 | POP BC | Character in display file at to-print location is same as character with index (26 - B)... | ||||||
| 37646 | LD A,B | ...so load B into A... | ||||||
| 37647 | SUB 26 | ...subtract 26... | ||||||
| 37649 | NEG | ...and negate to get index of character in A (e.g. A=0, B=1, C=2 ...) | ||||||
| 37651 | ADD A,65 | Add 65 to get ASCII index | ||||||
| 37653 | RET | Return | ||||||
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